Effects of magnesium flux cored wire on plasma arc "in-situ" welding of SiCp/6061Al MMCs

To sovle the problem of segregation of reinforcement particles in joint of SiCp/6061Al MMCs, which makes the tensile strength decreased, the SiCp/6061Al Matrix Composites were welded by plasma arc welding with flux cored wires in different magnesium content as filled composite and argon-nitrogen mixture as plasma gases, and the effect of this kind of flux cored wire on the microstructure and properties of welded joints was investigated. The results show that, with the mass fraction of magnesium reaches to 15% in wire, a poor welded-joint, serious splash and unstable arc will appeare, however, when it is less than 5%, a good and compact weld metal with stable arc and no splash will form. At the same time, the new phases of AlN, TiN and TiC are small, neither Mg ₂Si nor Al ₄C ₃ are found in the joint. All the strength and toughness of the joint have been improved. The maximum tensile strength of welded joint increases to 213 MPa, 67% of the matrix. Generally, the tensile fracture is brittleness fracture with a little toughness.